Technical Field
Embodiments of this disclosure relate to a belt unit including a belt, a transfer unit including a belt, and an image forming apparatus including the belt unit or the transfer unit.
Description of the Related Art
An image forming apparatus includes multiple units having various functions related to image formation within the apparatus body. These units are detachably supported in the apparatus body for the purpose of maintenance, cleaning, exchange of parts, and exchange of units. Such units include a belt unit or a transfer unit including an endless belt that is wound around a plurality of support rollers, which serve as supports and are members used in image transfer and image fixing or in conveyance of paper sheet, which serves as a recording medium.
In such a belt unit or a transfer unit, in the case that a belt is used, if a belt made of a multi-layer material including a base material, an elastic layer, and the like is used, the edges of the belt positioned in the belt width direction may become warped due to the influence of heat deformation caused by differences in the thermal expansion coefficient of each layer or temporal degradation. If the belt edges become warped, depending on the level of warping, the attachment/detachment of one unit may interfere with another adjacent unit or the like, and this interference may lead to breakage of the belt or obstruction of the attachment/detachment operation. Hence, a configuration is proposed in which a pressing member is disposed in a direction of warping of the belt edges, and the pressing member is supported by a contact-and-separation assembly that moves the pressing member in the up-down direction as necessary so as to prevent the belt warping from becoming larger.